Highly selective enrichment of baicalin in rat plasma by boronic acid-functionalized core–shell magnetic microspheres: Validation and application to a pharmacokinetic study

• Boronic acid-functionalized core-shell magnetic microspheres were synthesized.
• Rapid detection of baicalin in rat plasma based on magnetic microspheres.
• Baicalin was selectively extracted from biosamples only for a 10-min vortexing.
• Microsphere-adsorbed baicalin was isolated from the matrix using a magnet.
• The method could be used for drugs similar to baicalin.

To the best of our knowledge, this study is the first to successfully apply a novel, highly selective enrichment technique based on boronic acid-functionalized core–shell magnetic microspheres (BA-Fe3O4@SiO2–Au@mSiO2) with a large surface area and uniform pore size, to determine the baicalin concentration in rat plasma by HPLC. By taking advantage of the special interaction between boronic acid and baicalin under alkaline conditions, as well as the microspheres' size exclusion ability, baicalin was selectively extracted from protein-rich biosamples, such as plasma, without any other pretreatment procedure except for a 10-min vortexing step. BA-Fe3O4@SiO2–Au@mSiO2 microsphere-adsorbed baicalin was straightforwardly and rapidly isolated from the matrix using a magnet. Baicalin was subsequently eluted from the microspheres under acidic conditions for 2 min for further HPLC analysis. The extraction conditions, such as the amount of microspheres added, adsorption time, adsorption pH, and elution time and pH, were also determined. Furthermore, method validation, including the linear range, detection limit, precision, accuracy, and recovery, were determined. This newly developed method based on BA-Fe3O4@SiO2–Au@mSiO2 microspheres is a simple, accurate, selective, and green analytical preparatory technique for analyzing baicalin in rat plasma. This study will be further novel research on the analysis of complex plasma samples and the pharmacokinetics of drugs similar to baicalin.

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